Communication in buildings and personal area systems may be used in the monitoring or control of automation of, for example, energy management, sensors, monitoring, detectors, healthcare, security, access control, operators, actuators, locks, lighting, metering, climate systems, windows, shades, heating, entertainment, information devices and appliances (hereafter called automation). Communication may take place between a controller and a controllable device, between nodes, between a master and a slave or between a transmitter and a receiver. Control of automation may involve such communication among individuals or groups.
In relation to wireless communication and automation there is a need for secure communication of data and/or instructions. For example, EP1340198B1 provides a secure communication between a controller and a controllable device, by producing a challenge request which the controller from which the communication originates is able to authenticate by sending a MAC (Message Authentication Code). Such a challenge request and message authentication method ensures that no communication from foreign controllers or communication that has been tampered will be accepted by the receiver.
Synchronous communication may also be provided to a group, so the group can perform synchronized actions. In other cases, automation power consumption may be reduced by communication to a group. In still other cases, bandwidth occupation may be reduced by way of group communication. Some automation communications may have a drawback, however, which arises during communications with a group of nodes where all of the nodes in a group cannot communicate at the same time due to collisions between the communications. Consequently, a sequential communication system may be used to communicate with one node after another node. This system causes an unfortunate delay for some nodes. Further because automation communication often has low power consumption, the data bit rate is also low and this may increase the delay.
The sequential activation may, therefore, have an unfortunate effect, when for example 20 slaves (light sources) are dimmed where each dim is more or less delayed. Another example may be, when 5 electric window shades start to move to block the sun and each shade has a slight delay. Another example may be an automation status change, like a change in mode or scenario which is communicated to a group. Group communication may advantageously be synchronous or provide reduced power consumption.
It would be advantageous to provide communication for automation that eliminate or reduce the drawbacks mentioned above and further provide a number of advantages, for example reduced power consumption, because some products or controllers may be battery powered or powered by a limited or renewable energy source. Consequently it may be advantageous to limit the communication and data load, while still providing secure and reliable communication.